The British aid worker being held by Islamic State terrorists is a dad-of-two - while UK jihadists who tried to flee the savagery are also being held captive

Death sentence: British Islamic State butcher Jihadi John murdered Steven Sotloff

The SAS is poised to launch a dramatic bid to rescue a British aid worker being held hostage by the Islamic State thugs.

As special forces awaited orders to storm the terror group’s stronghold in Syria, the former head of the Navy said Jihadi John – the UK extremist believed to have beheaded two American journalists – is a “dead man walking”.

It has been revealed the Briton who has been threatened with becoming the next Westerner to be executed by the fanatics is a dad-of-two who was captured while working for a charity.

The middle-aged man was pictured on his knees in a horrific video released on Tuesday showing Jihadi John decapitating American Steven Sotloff.

David Cameron, who yesterday chaired a meeting of the Government’s emergency Cobra committee, vowed that Britain would do all it could to save the aid worker.

The PM tonight declared the UK would “not be cowed” by the “barbaric” killers and said IS should be “be squeezed out of existence.”

He added: “We’ve faced down threats like this before and we will do again.

“If they think we will weaken in the face of their threats, they are wrong. It will have the opposite effect. We will be more forthright in the defence of the values, liberty under the rule of law, freedom, democracy that we hold dear.”

The British hostage has 16 years of experience of humanitarian missions in dangerous places. Sources said he was captured near a refugee camp in north Syria nearly a year ago.

He was born in East Yorkshire and grew up in Perth in central Scotland.

PA

Determined: David Cameron condemned the "sickening and brutal murder"

The man is understood to have been married twice and has two daughters. He has lived for several years with his second wife near the Croatian capital Zagreb.

In the video showing the murder of Steven, hooded Islamic State savage Jihadi John said the British captive would be the next victim unless the West bowed to their demands.

Admiral Lord West, the former First Sea Lord, said the sickening actions of Jihadi John had made him a major priority.

After calling him a “dead man walking”, Admiral Lord West added: “Islamic State have clearly threatened British citizens and they’ve said they want to attack the UK.

“When you’re in that situation it’s very different, and everything in your armoury as a nation should be used.”

It is believed the British aid worker is being held at a compound in Raqqa. Two weeks before the film of Steven’s decapitation, an Islamic State video was released showing US journalist James Foley, 40, suffering the same fate.

Their murderer has a London accent and has become known as Jihadi John because he was one of a trio of captors nicknamed The Beatles by hostages.

Tonight Barack Obama arrived in Wales for the Nato summit.

Speaking earlier at a news conference in Estonia’s capital Tallinn, he said: “Our objective is clear and that is to degrade and destroy [Islamic State] so that it’s no longer a threat, not just to Iraq but also the region and to the United States.

“Whatever these murderers think they will achieve with killing innocent Americans like Steven, they have already failed. They failed because... Americans are repulsed by their barbarism. We will not be intimidated.”

Relatives of 31-year-old Steven, of Miami, have said they were “grieving privately”.

Despite his tough words, Mr Cameron’s anti-terror drive was thrown into fresh confusion yesterday after the Lib Dems continued to object to the plans.

The PM told MPs that measures to move terror suspects in Britain from their home area would definitely go ahead.

But this claim was denied by the Lib Dems who said they were still under discussion.